1. Field of the Invention
The invention relates to fuel carburetors. More particularly, the invention relates to the fuel bowl that supplies fuel to the main body of the carburetor.
2. Description of Related Art
Float bowls are conventionally used in carburetors. In the typical fuel system of an automobile, a fuel pump pushes fuel into the float bowl via an inlet. Disposed in the inlet is a needle-and-seat valve which is attached to a float. The float rises and falls with the level of the fuel in the float bowl, causing the needle-and-seat valve to either open or close. Vacuum from the venturi of the carburetor pulls fuel out of the float bowl through the metering block to which the float bowl is attached. When the fuel level in the float bowl falls, the float falls and opens the needle-and-seat valve, and fuel is allowed to enter the float bowl. When the fuel level rises, the float rises and closes the needle-and-seat valve, preventing excess or unnecessary fuel from entering the float bowl.
Race cars conventionally use various different types of fuel, such as gasoline, kerosene, alcohol, and the like. The use of different fuels may require the use of differently configured carburetors. In one example, a dual-fuel carburetor may use both gasoline and alcohol, with one fuel being supplied to one float bowl of the carburetor and the other fuel being supplied to the other float bowl on the opposite side of the carburetor. Such a carburetor is described in U.S. Pat. No. 4,415,507 to Voliva. The Voliva patent describes a modified Holley 4150-60 carburetor, in which gasoline is pumped into the inlet of a primary float bowl and alcohol is pumped into the inlet of a secondary float bowl. Other dual-fuel systems are described in U.S. Pat. Nos. 4,085,720 to Etoh and 3,807,377 to Hirschler, Jr. et al. In both of these systems, a switching device is provided to switch between two float bowls, each supplied with different fuel. Throttle conditions (e.g., pressure) determine when the switching device will select one fuel over the other.
In some cases, it is desirable (e.g., from a cost and/or performance standpoint) to modify an existing fuel system which is designed to run on one type of fuel so that it may run on a different type of fuel. For example, many race cars' fuel systems are initially designed to consume gasoline, and are subsequently provided alcohol. Owing to several factors, such as the augmented power requirements of racing vehicles, the automobile requires approximately twice as much alcohol as gasoline by volume per unit time.
A problem arises in how to deliver the lower-volatility alcohol to the venturi of the carburetor. Specifically, roughly twice as much fuel must be delivered through the float bowl in the same amount of time. A known previous method of rectifying this problem is to boost the fuel pressure in the fuel line by using a larger, more powerful fuel pump upstream of the float bowl of the carburetor. By using a fuel pump twice as powerful as the pump originally provided with the automobile, the requisite amount of alcohol can be delivered to the float bowl.
This method possesses several drawbacks. First, the needle-and-seat valve disposed in the inlet of the carburetor's float bowl is not designed to accommodate double the amount of pressure/flow. For example, most carburetor needle-and-seat valves are designed for 8 psig; however, the larger fuel pump increases fuel line pressure to roughly 16 psig. Consequently, the higher pressure forces the needle-and-seat valve to remain open constantly, and fuel is continuously fed to the float bowl regardless of the fuel level. As a result, fuel bleeds out of the float bowl, and ends up, among other places, in the oil pan. This necessitates changing the oil between each use of the automobile. Moreover, because the needle-and-seat valve never closes, it is impossible to control the amount of fuel being forced through the float bowl, thereby wasting much fuel. Finally, the requisite larger fuel pump is generally an expensive piece of equipment, and may actually be cost-prohibitive in some cases.
A problem exists, therefore, in modifying an existing gasoline carburetor for use with a fuel having lower volatility such as alcohol in a manner consistent with the ordinary use of the carburetor, and in a manner that is cost-effective.